Sauron
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Progress on Compressed Gases in Thailand
I now have a source for new gas cylinders locally and it is a relief that prices are very low.
These are full sized steel cylinders for 3000 psi, new, never filled, and including a brass manual control valve, CGA 540 (O2), 580 (Ar/N2/He) or 320
(CO2). Regulators can be attached at extra cost.
The 0.5 Q cylinders are about $50 while 1.5 Q ones are about $65.
Cost of gases:
Argon $6 per cylinder
Nitrogen $2.50 per cylinder
CO2 $4.50 per cylinder.
Dip tube for CO2 so I can attach a nozzle and cone for dry ice snow making $10
So I will own my own cylinders rather than renting them. I will need regulators for the N2 and Ar but not the CO2. Maybe I need to pass the N2 and Ar
through traps to remove moisture but such inline traps are available.
I think this sees to my inert atmosphere and dry ice on demand needs. I am still looking into H2 for catalytic hydrogenation and He for sparging HPLC
solvents.
So a full size cylinder is cheaper than an Aldrich lecture bottle, why does not this surprise me?
Dimensions
0.5 m3 cap. 35 x 13 cm or 57 x 10 cm
1.5 m3 cap 85 x 13 cm
Photos attached, the cyls shown are O2 marked.
--------------------------
I finally got a quote from the Harris agent for stainless steel control valves to fit Sure/Pac cylinders. The price in Thailand is $135, one third of
what the Aldrich agents wants for the same thing. These are diaphragm valves not needles valvles, 1/4" male NPT inles thread. I ordered 5 of them and
will order the Sure/Pac 900 cc bottles (mild steel) from the Aldrich agent. These are $75 each. So each bottle plus valve will run me $200, this is
acceptable for the vapor-over-liquid condensed corrosives like NH3, Cl2, SO2, etc. Also MeCl and MeBr.
[Edited on 20-9-2008 by Sauron]
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Sauron
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Those nominally 0.5 cubic meter bottles (the volume refers I am sure to the volume the contained O2 would be at 1 bar) correspond to US "E" and#20
cylinders respectively with internal volumes of 270 in3 and 220 in3 respectively and weighing empty about 10.5-11 lbs.
I do not see a standard US cylinder size anything like 13 x 85 cm. The #55 cylinder is 13 cm diameter (5.25") but is not that length. It does have
c.3X the volume of a #20 and weighs c. 35 lbs empty.
These "small" cylinders work out to be 3.6 to 4 liters internal volume, while the larger cylinder is about 11 liters. So I think I will use only the
900 cc Sure/Pac low pressure (240 psi) bottles for the liquified corrosives, as I do not think I will ever be condensing enough to bother with the 3.6
L high pressure cyls, and the Sure/Pacs are roughly same price.
[Edited on 20-9-2008 by Sauron]
[Edited on 20-9-2008 by Sauron]
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chemrox
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The gas vendors I deal with don't usually fill my cylinders but rather exchange them for ones previously filled. The result is that only standard
sizes are available. Usually this means 40 and 80 cf or welding bottle sizes. Only oxygen is filled in smaller bottles. I bought a 20 cf bottle at
harbor freight and exchanged it for a 30 for a few bucks more. I need an 80!
"When you let the dumbasses vote you end up with populism followed by autocracy and getting back is a bitch." Plato (sort of)
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Sauron
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Yes, this vendor is primarily a welding gas guy, and yes, he told me he usually only fills the 20 cyls with O2. The argon and N2 are typical MIG/TIG
grades, and I would like your opinion on whether or not that is good enough.
This guy is willing to sell me new bottles with brass valves and cheap. He will then fill/refill them fr me. He will swap the standard CGA 540 valve
for CGA 320 (CO2) or CGA 580 (Ar/N2/He). I can get single or dual stage US made regulators locally. The brass ones are nt so dear, the SS ones are
$600. That makes Hcl or HBr a little pricey on front end, but at least it's a one timer.
This supplier says he has never filled these sizes of cyl with He or H2 and he wants to know what grades I am after. He for me is for sparging HPLC
solvents and I will have to look up what Waters recommends. H2 is for cat.hydrogenation so needs to be dry and O2 free.
For higher grades and other specialty gases that this guy does not sell I have to deal with Thai Industrial Gases, but they already told me they will
fill my cyls for me. My recollection is that for used cylinders they will only refill with same gas. New cylinders no problem but you need an
appropriate valve and regulator. They sell CONCOA gas hardware. My other main contact here is with the Hassis agent. Both are US companies.
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Klute
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Those are really nice prices!
IME, MIG/TIG argon is perfectly suitable for most needs. the major contaminat is CO2, but we are talking <0.1-0.01% on the common grades. The
humidity isn't a problem, even the lowest grades keep NaOH/KOH perfectly free flowing after emptying a 50l (NPTC) of argon throught them.
KOH/NaOh are evry good at drying and removing CO2. You can dilute the granules with vermiculite to have a better contact and less compact material
(much less charge losses).
\"You can battle with a demon, you can embrace a demon; what the hell can you do with a fucking spiritual computer?\"
-Alice Parr
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Sauron
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The single stage regulator suitable for use with N2, Ar and He and instock locally is Harris Model 825. This is a brass two gauge regulator usually
set up for delivery pressured up to 150 psi which is fine for glove box and inert atmosphere work in glass (obviously more than adequate.) I won't
need He till my HPLC systems go online, so I have not reviewed the sparging requirements for the prep systems but most likely this will do for that as
well.
The good news is that this US made regulator is <$100. In fact about $70. I'll post the spec sheet as soon as I receive it. The Model 601 is
c.$35. Note that some of these mat be available in USA/Canada but are available in EU and cetainly Thailand. I know the 601 is available in USA. It's
825 I am not sure about.
While some of these are suitable for H2 as well, their delivery pressure restrictions limit then to low pressure hydrogenation apparatus like Parr
shakers. For higher pressure stirred hydrogenator bombs, a different regulator would be needed capable of delivering H2 in the range of 1000-1900 psi.
[Edited on 22-9-2008 by Sauron]
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Sauron
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Regulators for higher delivery pressures cost a bit more than for lower delivery pressures. The gas service must be specified (argon versus N2 versus
He versus air and so on).
Prices get wild and crazy when dealing with corrosive gases as the regulators must be stainless steel throughout. A typical single stage SS regulator
is $500-$600 or more not including the manual cylinder valve also SS. So HCl, HBr etc are expensive in terms of initial capital costs.
[Edited on 22-9-2008 by Sauron]
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Sauron
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My stainless steel Harris diaphragm valves with the correct thread for Aldrich Sure-Pac cylinders have arrived. The thread is 1/4 NPTM on inlet side
(what screws into the cylinder) and 1/4 NPTF on outlet side.
So I went hunting for odds and ends to complete these and also to allow use of same valves with Aldrich lecture bottles. Those are 3/8 NPT so first I
needed a reducing bushing in SS316 to take that down to 1/4 NPTF.
No problem, Swagelok and in stock in Bangkok, and quite cheap.
Next I needed a variety of hose barb connectors all 1/4 NPTM, Swagelok had 6 sizes in SS316 (or brass) from 1/8" through 1/2" tubing ID (barb) and
again all in stock locally and cheap.
Finally as most of these will be for liquified gases I wanted dip tubes (outage tubes) to run to bottom of cylinder interior so the contents are
withdrawn as liquid. SS316, with adapter built in 1/4 NPTM x 1/4 NPTF, and 19.4 inches long. In stock locally and about $40.
So I give Swagelok really high marks for professionalism. I fully expected to be raped on price as usual, and to have to wait 30-60 days for delivery
from US but no.
The Harris valves were supposed to come in 30 days and took 60.
My Frigimat Jr dry ice maker won't be here for another 4-5 weeks (Cole Parmer) and this $120 item is costing me $250.
I wish Swagelok made one, is all I can say. Cole Parmer sucks.
I will be going back to Swagelok for more hose barbs in brass for non corrosive compressed gases (N2, Ar, H2, He) Great company!
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Sauron
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I have now received Frigimat JR from Cole Parmer and installed it on a on a 6 cubic meter (48 liter) cylinder of liquid CO2 with a brass CGA320 valve
and a dip tube as required.
I installed the PE collector bag and opened the valve 3/4 turn as instructed. NOTE that is 75% of a turn NOT 3 to 4 turns! Dry ice flakes form
rapidly, the operation is quite noisy as you might expect from high pressure flow through a small orifice.
Test completed, I uninstalled the Frigimat and replaced the valve-protecting cap on the cylinder ring for safety.
It works.
I will see how much dry ice flakes I obtain, but it really does not matter. The cylinder and valve and Frigimat are all mine. CO2 refills are cheap
and I can easily have a spare cylinder on hand to use while the first is being refilled. All in all this is a convenient way to have dry ice flakes on
demand anytime for acetone -74 C slurries as required, rather than having to purchase slabs of dry ice which sublime almost as you watch and are not
in an ideal slurriable form even when you break them up with a hammer.
The Frigimat JR is overpriced but any of you can easily put one together from off the shelf brass pipe fittings and a plastic cone improvised from a
drinking cup or something similar.
Proceeding from cylinder end to business end, the components are
1. CGA 320 regulator nutto be retained on:
2. 2 inch x 1/4 NPTM (both ends) brass pipe nipple One end is mated to a brass hex nut flush with end. This retains the brass CGA cap. A nylon sealing
gasket washer is used. (Items 1 and 2 often sold together as "CGA320 regulator nut and nipple" along with special nylon washer and hex nut.) Other end
screws into
3. 45 degree (90 degree also will work) brass elbow, 1/4 NPTF both faces, forward face is mated with
4. Reducing bushing, brass, 1/4 NPTM x 3/8 NPTF which is closed with
5. 3/8 NPTM hex plug, brass, modified by drilling a 1/8" hole through. This is the liquid CO2 nozzle and there is a flat washer between it and the
reducer, then the plastic cone which has been drilled to be retained between the reducer and the plug with flat washers on both sides. A snap-on
wrench with long extension is of assistance in tightening up the plug inside the cone, But this can be done well enough without such a tool.
I estimate all that at no more than $15 worth of off the shelf hardware. A drill or drill press would be convenient, but not absolutely necessary.
[Edited on 20-12-2008 by Sauron]
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